Method of manufacturing light emitting module, and light emitting module

ABSTRACT

The method of manufacturing a light emitting module includes: providing a light guiding plate having a first main surface serving as a light emitting surface; and a second main surface positioned opposite to the first main surface and provided with a recess; providing a light adjustment portion containing a fluorescent material; providing a light emitting element unit in which a light emitting element comprising an electrode is integrally bonded to the light adjustment portion; bonding the light adjustment portion of the light emitting element unit to the recess; and forming wiring on the electrode of the light emitting element.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2018-059064, filed on Mar. 26, 2018, and Japanese Patent Application No.2019-056065 filed on Mar. 25, 2019, the disclosures of which are herebyincorporated by reference in their entirety.

BACKGROUND 1. Field of the Invention

The present disclosure relates to a method of manufacturing a lightemitting module, and a light emitting module.

2. Description of the Related Art

Light emitting devices using light emitting elements such as lightemitting diodes are widely used as light sources of backlights forliquid crystal displays, and various light sources for displays.

For example, a light source device as disclosed in Japanese PatentPublication No. 2015-32373A includes a plurality of light emittingelements mounted on a mounting substrate, hemispherical lens memberseach encapsulating the light emitting elements, and a light diffusionmember to which light from the light emitting elements enters, the lightdiffusion member being disposed on the hemispherical lens member.

Further, in a light source device as disclosed in Japanese PatentPublication No. 2016-115703A, a two-layer sheet obtained by integratinga encapsulating resin layer with a fluorescent material layer is bondedto the upper surface of a light emitting element, and the lateralsurface of the light emitting element is covered with a reflectingresin.

However, in the light source device disclosed in JP2015-32373A, thedistance between the mounting substrate and the diffusion plate shouldbe greater than the thickness of the lens member, so that there is apossibility to fail sufficient thickness reduction. In addition, thelight source device in JP2016-115703A cannot uniformly disperse andirradiate light from a plurality of light emitting elements, and thuscannot be used in applications which require light emissioncharacteristics with little luminance non-uniformity.

The present disclosure is intended to provide a method of manufacturinga light emitting module, and a light emitting module, where the lightemitting module is reduced in thickness, and is capable of uniform lightemission with little luminance non-uniformity.

SUMMARY

A method of manufacturing a light emitting module according to oneaspect of the present disclosure has providing a light guiding plate anda light emitting element unit. The light guiding plate has a first mainsurface serving as a light emitting surface, and a second main surfaceopposite to the first main surface. The second main surface defines arecess on it. The light emitting element unit has a light emittingelement having a light emission surface and comprising an electrode, anda light adjustment portion containing a fluorescent material. The lightemitting element is integrally bonded to the light adjustment portion.The method also has fixing the light emitting element unit to the lightguiding plate by bonding the light adjustment portion to the recess, andforming wiring on the electrode of the light emitting element.

The method of manufacturing a light emitting module can provide a lightemitting module including a light guiding plate and a light emittingelement, the light emitting module attaining uniform light emission withlittle luminance non-uniformity while having a reduced thickness as awhole. This is because a light adjustment portion is bonded to a recessof the light guiding plate, and a light emitting element unit in whichthe light emitting element is bonded to the light adjustment portion isdisposed at a predetermined position on the light guiding plate.Further, the method of manufacturing a light emitting module has such afeature that the light emitting element unit includes the fluorescentmaterial-containing light adjustment portion and the light emittingelement as an integral structure, and the light adjustment portion ofthe light emitting element unit is bonded to the recess of the lightguiding plate to dispose the light emitting element unit at apredetermined position on the light guiding plate. The light emittingelement unit is bonded at a predetermined position with high accuracywith less relative positional deviation of the light adjustment portion,the light emitting element and the recess of the light guiding plate, sothat light emitting modules having a reduced thickness as a whole can beefficiently mass-produced, and luminance non-uniformity of a surface ofthe light guiding plate can be reduced.

A light emitting module according to another aspect of the presentdisclosure has a light-transmissive light guiding plate, a lightemitting element unit. The light-transmissive light guiding plate has afirst main surface serving as a light emitting surface from which lightexits and a second main surface opposite to the first main surface. Thesecond main surface defines a recess on it. The light emitting elementunit is fixed to the recess of the light guiding plate. The lightemitting element unit has a light emitting element having a lightemission surface and a light adjustment portion containing a fluorescentmaterial, and a bonding wall. The light adjustment portion is integrallybonded to the light emitting element. Also, the light adjustment portionhas an insertion portion disposed in the recess. The insertion portionhas an outline smaller in size than an inner surface outline of therecess. The bonding wall is formed with a light-transmissive bondingagent filled in a ring gap formed between the insertion portion and therecess.

The light emitting module has such a feature that a light emittingelement unit a fluorescent material-containing light adjustment portionis bonded to a light emission surface of a light emitting element isbonded to a recess of a light guiding plate. Furthermore, the outline ofan insertion portion of the light emitting element unit, which isdisposed in the recess, is smaller in size than the inner shape of therecess of the light guiding plate, and a bonding wall formed using alight-transmissive bonding agent supplied in a ring gap formed betweenthe insertion portion and the recess. This can allow the light emittingmodule to have light emission characteristics with little luminancenon-uniformity and to have reduced thickness as a whole. This is becausethe insertion portion of the light emitting element unit is disposed inthe recess of the light guiding plate, the light-transmissive bondingwall is provided between the insertion portion of the light emittingelement unit and the recess, and the light emitting element unit isaccurately disposed at a predetermined position in the recess of thelight guiding plate, so that light emitted from the light emittingelement can enter into the light guiding plate through the lightadjustment portion, be diffused at the light guiding plate, and exitoutside.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of each part of aliquid crystal display device according to an embodiment of the presentdisclosure.

FIG. 2 is a schematic plan view of a light emitting module according tothe embodiment.

FIG. 3 is a partially enlarged schematic sectional view of the lightemitting module according to the embodiment, where the light emittingmodule is upside down with a light guiding plate positioned on the lowerside.

FIG. 4 is a schematic bottom view of a light emitting module accordingto another embodiment of the present disclosure.

FIG. 5 is a schematic bottom view showing a quadrangular insertionportion formed obliquely with respect to a quadrangular recess.

FIG. 6 is a schematic bottom view showing a quadrangular insertionportion formed parallel with respect to a quadrangular recess.

FIG. 7 is a sectional view showing the surface of a bonding wall lowereddue to slight difference in filling amount of a bonding agent.

FIG. 8 is a sectional view showing the surface of a bonding wall raiseddue to slight difference in filling amount of a bonding agent.

FIGS. 9A to 9D are enlarged schematic sectional view showing an exampleprocess of manufacturing a light emitting element unit according to anembodiment of the present disclosure.

FIGS. 10A to 10D are enlarged schematic sectional view showing anexample process of manufacturing a light emitting element unit accordingto an embodiment of the present disclosure.

FIGS. 11A to 11C are enlarged schematic sectional view showing oneexample process of manufacturing a light emitting module according tothe embodiment.

FIGS. 12A to 12C are an enlarged schematic sectional view showing anexample process of manufacturing a light emitting module according to anembodiment of the present disclosure.

FIG. 13 is an enlarged schematic sectional view showing an example inwhich a circuit board is connected to the light emitting module shown inFIG. 3.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, the present disclosure will be described in detail withreference to the drawings. In the following descriptions, terms showinga specific direction or position (e.g. “upper”, “lower” and other termsrelating to such terms) are used as necessary, but these terms are usedfor ease of understanding of the disclosure by referring to thedrawings, and the meaning of these terms does not limit the technicalscope of the present disclosure. In the following description, inprinciple, identical name and reference character denote an identical orsimilar member.

Further, embodiments described below are intended to give an example ofa light emitting module and a method of manufacturing the light emittingmodule for embodying the technical idea of the present disclosure, anddo not limit the present disclosure to the following embodiments. Inaddition, unless otherwise specified, the dimensions, materials, shapes,relative arrangements and so on of components described below are notintended to limit the scope of the present disclosure thereto, but areintended to give an example. In addition, details described in certainembodiment or example is also applicable to other embodiments orexamples. In addition, the sizes, positional relations and so on ofmembers shown in the drawings may be exaggerated for clarification ofexplanation.

Liquid Crystal Display Device 1000

FIG. 1 is a block diagram showing a configuration of each part of aliquid crystal display device 1000 including a light emitting module 100according to an embodiment. The liquid crystal display device 1000 shownin FIG. 1 includes a liquid crystal panel 120, two pieces of lens sheets110 a and 110 b, a diffusion sheet 110 c and a light emitting module100. The liquid crystal display device 1000 shown in FIG. 1 is aso-called direct backlighting liquid crystal display device in which thelight emitting module 100 is stacked under the liquid crystal panel 120.The liquid crystal display device 1000 irradiates the liquid crystalpanel 120 with light emitted from the light emitting module 100. Inaddition to the above-described constituent members, members such as apolarizing film and a color filter may be provided.

Light Emitting Module 100

FIGS. 2 and 3 show a configuration of the light emitting module of thisembodiment. FIG. 2 is a schematic plan view of the light emitting moduleaccording to this embodiment. FIG. 3 is a partially enlarged schematicsectional view showing the light emitting module according to thisembodiment, where the light emitting module is upside down with a lightguiding plate positioned on the lower side.

The light emitting module 100 shown in these drawings includes a lightguiding plate 1, and a plurality of light emitting element units 3respectively disposed in one of recesses 1 b of the light guiding plate1. In the light emitting module 100 shown in these drawings, a pluralityof recesses 1 b is provided on one light guiding plate 1, and the lightemitting element units 3 are respectively bonded to the recesses 1 b.However, the light emitting module may have a configuration of a lightemitting module 100′ shown in a schematic bottom view of FIG. 4, inwhich one recess 1 b is formed on a light guiding plate 1′, the lightemitting element unit 3 is bonded to the recess 1 b to form a lightemitting bit 5, and a plurality of light emitting bits 5 is arranged.Further, in the light emitting module 100 shown in FIG. 3, the lightemitting element units 3 are each provided with a first encapsulatingresin 15A which has outer lateral surfaces flush with the outer lateralsurfaces of a light adjustment portion 10 and in which a light emittingelement 11 is embedded, and a second main surface 1 d of the lightguiding plate 1 to which the light emitting element unit 3 is bonded isprovided with a second encapsulating resin 15B in which the lightemitting element unit 3 is embedded.

In the light emitting element unit 3, the light emitting element 11 isbonded to a surface of the light adjustment portion 10 on which awavelength conversion portion 12 is present. The light emitting element11 has an upper surface as an electrode-formed surface 11 d and a lowersurface as a light emission surface 11 c. The light emitting element 11irradiates the light adjustment portion 10 by emitting light mainly fromthe light emission surface 11 c. In the light emitting module 100 shownin FIGS. 2 and 3, the light emitting element units 3 are respectivelyarranged in recesses 1 b provided in a matrix form on the light guidingplate 1, and bonded to the light guiding plate 1. The light guidingplate 1 has a first main surface 1 c and a second main surface 1 d, thefirst main surface 1 c serving as a light emitting surface from whichlight exits, the second main surface 1 d being provided with a pluralityof recesses 1 b. In the recess 1 b, a part of the light emitting elementunit 3, in other words, the light adjustment portion 10 is positioned inthe drawing. The light adjustment portion 10 shown in FIG. 2 includesthe wavelength conversion portion 12 and a light diffusion portion 13stacked on the wavelength conversion portion 12. The light adjustmentportion 10 includes the wavelength conversion portion 12 stacked on thelight emitting element 11 side, and the light diffusion portion 13stacked on the light guiding plate 1 side. In the light adjustmentportion 10, light transmitted through the wavelength conversion portion12 is diffused by the light diffusion portion 13, and applied to thelight guiding plate 1, so that light exiting from the light guidingplate 1 can be made more uniform.

The light emitting module 100 according to the present disclosure canhave a reduced thickness as a whole because the recess 1 b is providedon the light guiding plate 1, and the light emitting element unit 3, towhich the light adjustment portion 10 including the wavelengthconversion portion 12 is bonded, is disposed in the recess 1 b. Therecess 1 b is provided on the light guiding plate 1, and the lightemitting element unit 3 is disposed in and bonded to the recess 1 b,positional deviation of the light emitting element unit 3 and the lightguiding plate 1 can be more reliably alleviated as compared to a lightemitting module in which a light emitting element is mounted on a wiringsubstrate, and then light guiding plates are combined. In particular, inthe light emitting module 100, the light emitting element unit 3 havingan integral configuration of the light emitting element 11 and the lightadjustment portion 10 with the wavelength conversion portion 12 bondedto the light emitting element 11 is disposed in the recess 1 b of thelight guiding plate 1. Thus both the wavelength conversion portion 12and the light emitting element 11 can be disposed at a predeterminedposition on the light guiding plate 1 with high accuracy to attainfavorable optical characteristics. In particular, the light emittingmodule 100 in which light from the light emitting element 11 istransmitted through the wavelength conversion portion 12, guided to thelight guiding plate 1, and exits outside can realize mounting with lesspositional deviation of the light emitting element 11, the wavelengthconversion portion 12 and the light guiding plate 1. This can improvelight emission characteristics in relation to, for example, colornon-uniformity and luminance non-uniformity of light exiting outsidefrom the light guiding plate 1, to thereby achieve good light emissioncharacteristics.

In a direct backlighting liquid crystal display device, the distancebetween a liquid crystal panel and a light emitting module is small, andtherefore color non-uniformity and luminance non-uniformity of the lightemitting module may cause color non-uniformity and luminancenon-uniformity of the liquid crystal display device. Thus, a lightemitting module with little color non-uniformity and luminancenon-uniformity is desired as a light emitting module for a directbacklighting liquid crystal display device.

Employing the configuration of the light emitting module 100 of thisembodiment can reduce luminance non-uniformity and color non-uniformitywhile reducing the thickness of the light emitting module 100 to 5 mm orless, 3 mm or less, 1 mm or less or the like.

Members that form the light emitting module 100 according to thisembodiment, and methods of manufacturing the members will be describedin detail below.

Light Guiding Plate 1

The light guiding plate 1 is a light-transmissive member in which lightincident from a light source is formed into a planar shape, and exitsoutside. As shown in FIG. 2, the light guiding plate 1 in thisembodiment has a first main surface 1 c as a light emitting surface, anda second main surface 1 d positioned on a side opposite to the firstmain surface 1 c. The light guiding plate 1 is provided with a pluralityof recesses 1 b formed on the second main surface 1 d and a V-shapedgroove 1 e provided between adjacent recesses 1 b. A part of the lightemitting element unit 3 is positioned in the recess 1 b. Inserting apart of the light emitting element 11 into the recess 1 b of the lightguiding plate 1 can reduce the thickness of the light emitting module asa whole. The light guiding plate 1 is provided with a plurality ofrecesses 1 b, and the light emitting element units 3 are respectivelydisposed in the recesses 1 b to form the light emitting module 100 asshown in FIGS. 2 and 3, or one light emitting element unit 3 is disposedon the light guiding plate 1′ with one recess 1 b to form the lightemitting bit 5, and a plurality of light emitting bits 5 is arranged ona plane to form the light emitting module 100′ as shown in FIG. 4. Inthe light guiding plate 1 provided with a plurality of recesses 1 b, atleast one grid-like V-shaped groove 1 e is formed between recesses 1 bas shown in FIG. 3. The light guiding plate 1 provided with one recess 1b has an inclined surface 1 f inclined downward toward the outerperipheral edge on an outer peripheral portion of the second mainsurface 1 d as shown in FIG. 4.

The V-shaped groove 1 e and the inclined surface 1 f are provided withan encapsulating resin 15 which reflects light as described later. Theencapsulating resin 15 supplied in the V-shaped groove 1 e is preferablyformed using a white resin which reflects light, and the encapsulatingresin 15 of white resin can alleviate incidence of light emitted fromthe light emitting element 11 to a neighboring light guiding plate 2sectioned by the V-shaped groove 1 e, so that light from each lightemitting element 11 is less likely to leak to a neighbor. Theencapsulating resin 15 bonded to the inclined surface 1 f provided on anouter peripheral portion of the second main surface 1 d of one lightguiding plate 1 can alleviate leakage of light to the periphery of thelight guiding plate 1, to thereby alleviate an intensity decrease oflight emitted from the first main surface 1 c of the light guiding plate1.

The size of the light guiding plate 1 is appropriately determinedaccording to the number of recesses 1 b, and for example, the lightguiding plate 1 with a plurality of recesses 1 b may have a size in arange of about 1 cm to about 200 cm, preferably about 3 cm to about 30cm, on each side. The light guiding plate 1 may have a thickness in arange of about 0.1 mm to about 5 mm, preferably about 0.5 mm to about 3mm. The planar shape of the light guiding plate 1 may be a substantiallyrectangular shape, a substantially circular shape or the like.

As a material for the light guiding plate 1, optically transparentmaterials such as resin materials including a thermoplastic resins andthermosetting resins, or glass. Example thermoplastic resins includeacrylic, polycarbonate, a cyclic polyolefin, polyethylene terephthalateor polyester. Example thermosetting resins include epoxy or silicone. Inparticular, thermoplastic resin materials are preferable because theycan be efficiently processed by injection molding. In particular,polycarbonate is preferable because it has high transparency and isinexpensive. For a light emitting module which is manufactured withoutbeing exposed to a high-temperature environment as in reflow solderingin a manufacturing process, even a thermoplastic material having lowheat resistance, such as polycarbonate, can be used.

The light guiding plate 1 can be molded by, for example, injectionmolding or a transfer mold. The light guiding plate 1 can be formed intoa shape having recesses 1 b by a mold, and mass-produced at low costwhile positional deviation of recesses 1 b is reduced. However, thelight guiding plate can also be provided with recesses by cuttingprocessing, for example, with a NC processing machine after being moldedinto a plate shape.

The light guiding plate 1 in this embodiment may be formed with a singlelayer, or multilayer formed by stacking a plurality oflight-transmissive layers. When employing a multilayered light guidingplate, one or more layers having different refractive indices, forexample, a layer of air, is provided between appropriately selectedlayers. Accordingly, light is more easily diffused, so that a lightemitting module with reduced luminance non-uniformity can be obtained.Such a configuration can be obtained by, for example, providing a spacerbetween appropriately-selected light-transmissive layers to separate thelayers, and providing a layer of air. In addition, on the first mainsurface 1 c of the light guiding plate 1, a light-transmissive layer,and a layer having a different refractive index, e.g. a layer of air,between the first main surface 1 c of the light guiding plate 1 and thelight-transmissive layer may be provided. Accordingly, light is moreeasily diffused, so that a liquid crystal display device having reducedluminance non-uniformity can be obtained. Such a configuration can beobtained by, for example, providing a spacer in at least oneappropriately-selected layer between the light guiding plate 1 andlight-transmissive layer to separate the light guiding plate 1 and thelight-transmissive layer, to thereby provide a layer of air.

Optically Functional Portion 1 a

The light guiding plate 1 may include an optically functional portion 1a on the first main surface 1 c side. The optically functional portion 1a can have a function of, for example, spreading light in the surface ofthe light guiding plate 1. For example, a material different inrefractive index from the material of the light guiding plate 1 isprovided. Specifically, it is possible to use a recess which is formedon the first main surface 1 c side, and has an inverted cone shape, oran inverted polygonal pyramid shape such as an inverted quadrangularpyramid shape or an inverted hexagonal pyramid shape, or an invertedtruncated cone shape, an inverted truncated polygonal pyramid shape orthe like and which reflects applied light in a lateral direction of thelight emitting element unit 3 at an interface between the inclinedsurface of the recess and the material different in refractive indexfrom the light guiding plate 1 (e.g. air). In addition, for example, therecess 1 b having an inclined surface and provided with alight-reflective material (e.g. a reflecting film of metal or the like,or a white resin) or the like may also be used. The inclined surface ofthe optically functional portion 1 a may be a straight line or a curvedline in sectional view. As described later, the optically functionalportion 1 a is preferably provided at a position corresponding to eachlight emitting element unit 3, in other words, a position on a sideopposite to the light emitting element unit 3 disposed on the secondmain surface 1 d side. In particular, the optical axis of the lightemitting element unit 3 is preferably substantially coincident with theoptical axis of the optically functional portion 1 a. The size of theoptically functional portion 1 a can be appropriately determined.

Recess 1 b

The light guiding plate 1 is provided with the recess 1 b formed on thesecond main surface 1 d side. A part of the light emitting element unit3 is disposed at a predetermine position inside the recess 1 b. Therecess 1 b shown in FIG. 3 has a shape obtained by cutting off a part ofthe second main surface 1 d. The recess can also be provided inside aprojection formed in a ring shape on the second main surface (notshown). The inner surface outline of the recess 1 b has a size largerthan that of the outline of an 17 for disposing the light emittingelement unit 3 in the recess 1 b, and a ring gap 18 is formed betweenthe inner periphery of the recess 1 b and the outer periphery of theinsertion portion 17 of the light emitting element unit 3 in a statewhere the insertion portion 17 of the light emitting element unit 3 isdisposed. The ring gap 18 is filled with a bonding agent 14 to form abonding wall 19. The inner surface outline of the recess 1 b is formedsuch that the volumetric capacity of the ring gap 18 is larger than thevolume of the insertion portion 17 of the light emitting element unit 3.In the light emitting module of this embodiment, the light adjustmentportion 10 is disposed in the recess 1 b of the light guiding plate 1,and therefore the light adjustment portion 10 is used as the insertionportion 17 of the light emitting element unit 3. The insertion portion17 of the light emitting element unit 3 may include not only the lightadjustment portion 10, but also applied as the light adjustment portion10 and a part of the light emitting element 11 in the recess 1 b.

The volumetric capacity of the ring gap 18 is, for example, not lessthan 1.2 times, preferably not less than 1.5 times, and more preferablynot less than 2 times the volume of the insertion portion 17 of thelight emitting element unit 3. The ring gap 18 may be filled with thebonding agent 14 to form the bonding wall 19. In the light guiding plate1 shown in FIG. 4, the inner surface outline of the recess 1 b may havea quadrangular shape, and the outline of the insertion portion 17 of thelight emitting element unit 3 disposed in the recess 1 b may have aquadrangular shape. The quadrangular insertion portion 17 is disposed inthe recess 1 b with an orientation in which each side crosses thequadrangular recess 1 b, in other words, an orientation in which theinsertion portion is rotated with respect to the quadrangular recess 1b, so that the ring gap 18 is provided between the recess 1 b and theinsertion portion 17. The insertion portion 17 in this drawing ispositioned in the recess 1 b with an orientation in which each side isinclined at 45 degrees. The recess 1 b in which the insertion portion 17is disposed with this orientation has an inner surface outline having asize at least 2 times the size of the outline of the insertion portion17.

The light guiding plate 1 with the insertion portion 17 disposed in therecess 1 b with an orientation shown in FIG. 5 has such a feature thatluminance non-uniformity on the first main surface 1 c can be reduced.This is because light emitted from each lateral surface of the insertionportion 17 to the periphery is intensely radiated in the direction ofarrow A shown by a chain line in FIG. 5, so that region C in FIG. 5 isbrightly irradiated. In the quadrangular insertion portion 17, theintensity of light in an arrow A direction orthogonally crossing eachside is higher than the intensity of light radiated in an arrow Bdirection from a corner. In FIG. 5, region C is positioned at a greaterdistance from the insertion portion 17 than region D, and thereforetends to be dark. However, light is more intense in an arrow A directionthan in an arrow B direction, thus luminance decrease can be alleviated,resulting in reduction of luminance non-uniformity. When thequadrangular insertion portion 17 is disposed in the quadrangular recess1 b with an orientation in which the sides of the insertion portion 17are parallel to the sides of the recess 1 b as shown in FIG. 6, region Cis positioned at a greater distance from the insertion portion 17 thanregion D, and the intensity of light radiated from the insertion portion17 decreases, so that the luminance is lower in region C than theluminance in region D.

The recess 1 b having an inner surface outline larger in size than theoutline of the insertion portion 17 has such a feature that luminancenon-uniformity can be alleviated by increasing flexibility in angle oforientation in which the insertion portion 17 is disposed. This caneliminate surface level difference caused by unevenly supplying thebonding agent 14 in the ring gap 18, so that a preferable lightdistribution can be achieved at the outer peripheral of the recess 1 b.The ring gap 18 is filled with the bonding agent 14 to form thelight-transmissive bonding wall 19, and supplying uneven amount of thebonding agent 14 makes the surface level uneven, resulting inundesirable light emission. FIGS. 7 and 8 shows a state in whichsupplying uneven amount of the bonding agent 14 makes the liquid surfacelevel of the bonding wall 19 uneven. FIG. 7 shows a state in which thesupplying amount of the bonding agent 14 is excessively small. Thesurface level of the bonding wall 19 is lower than the second mainsurface 1 d of the light guiding plate 1, and decreases to the inside ofthe ring gap 18, so that an air gap is generated between the lightguiding plate 1 and the insertion portion 17. FIG. 8 shows a state inwhich the supplying amount of the bonding agent 14 is excessively large.In this case, the bonding agent 14 for forming the bonding wall isleaked out from the ring gap 18, and overruns on the second main surface1 d. The bonding agent 14 put in a gap between the light guiding plate 1and the insertion portion 17 and rising on the second main surface 1 dchanges a path of light incident to the light guiding plate 1 from theinsertion portion 17, resulting in undesirable light emission.

The volumetric capacity of the ring gap 18 can be made larger than thevolume of the insertion portion 17 by having the inner surface outlineof the recess 1 b larger in size than the insertion portion 17. Thisstructure can reduce unevenness of the liquid surface level due tovariations of supplying amount of the bonding agent 14 in the ring gap18, so that preferable light emission can be obtained in regions of thelight guiding plate 1 and the insertion portion 17.

In consideration of the outline of the insertion portion 17 and thecharacteristics described above, the size of the recess 1 b in a planview may be, for example, in a range of 0.05 mm to 10 mm, preferably 0.1mm to 2 mm, in terms of a diameter in a circular shape, a long diameterin an elliptical shape, and a length of a diagonal in a quadrangularshape. The depth of the recess 1 b may be in a range of 0.05 mm to 4 mm,preferably 0.1 mm to 1 mm. The distance between the optically functionalportion 1 a and the recess 1 b can be appropriately determined as longas the optically functional portion 1 a and the recess 1 b are separatedfrom each other. The shape of the recess 1 b in a plan view may be, forexample, a substantially rectangular shape or a substantially circularshape, and can be selected according to arrangement pitches of recesses1 b or the like. The arrangement pitches of the recesses 1 b (i.e.,distances between the centers of two recesses 1 b closest to each other)may be substantially equal. Preferably, the shape of the recess 1 b in aplan view is a substantially circular shape or a substantially squareshape. In particular, the recess 1 b having a substantially circularshape in a plan view can desirably spread light from the light emittingelement unit 3.

Light Emitting Element Unit 3

The light emitting element unit 3 is a light source for the lightemitting module 100. In the light emitting element unit 3, the lightadjustment portion 10 with the wavelength conversion portion 12 isbonded to the light emitting element 11 as shown in FIG. 3. Further, inthe light emitting element unit 3 in this embodiment, the outer lateralsurfaces of the first encapsulating resin 15A for embedding the lightemitting element 11 are flush with the outer lateral surfaces of thelight adjustment portion 10. The light emitting element unit 3 isdisposed in the recess 1 b of the light guiding plate 1 to emit lightoutside through the light guiding plate 1. The light emitting elementunit 3 in the drawing is disposed inside the recess 1 b by disposing thelight adjustment portion 10 as the insertion portion 17 in the recess 1b of the light guiding plate 1. The light emitting element unit 3 hasthe light adjustment portion 10 bonded to the bottom of the recess 1 bformed on the light guiding plate 1.

The light emitting element unit 3 shown in FIG. 3 has the lightadjustment portion 10 bonded to the light emission surface 11 c of thelight emitting element 11. In the light emitting element 11, the lightadjustment portion 10 is bonded to the light emission surface 11 c suchthat a surface opposite to the electrode-formed surface 11 d serves asthe light emission surface 11 c. In the light emitting module of thisembodiment, a facedown type is employed in which the light emissionsurface 11 c is positioned on a side opposite to the electrode-formedsurface 11 d, and the light emission surface 11 c serves as a main lightemitting surface, but a light emitting element of faceup type can alsobe used. In the light emitting element 11 shown in FIG. 3, a surfaceopposite to the light emission surface 11 c serves as theelectrode-formed surface 11 d, and the electrode-formed surface 11 d isprovided with a pair of electrodes 11 b. A pair of electrodes 11 b iswired and is electrically connected in a structure as described later.The light emitting element unit 3 and the light guiding plate 1 arebonded to each other with the light-transmissive bonding agent 14 formedof a material using a light-transmissive resin.

For example, the light emitting element 11 includes a light-transmissivesubstrate of sapphire or the like, and a semiconductor layered structurestacked on the light-transmissive substrate. The semiconductor layeredstructure includes a light emitting layer, and an n-type semiconductorlayer and a p-type semiconductor layer. The light emitting layer isinterposed between the n-type semiconductor layer and the p-typesemiconductor layer. The n-type semiconductor layer and the p-typesemiconductor layer are electrically connected to at least one n-sideelectrode and at least one p-side electrode 11 b, respectively. In thelight emitting element 11, for example, the light emission surface 11 cof a light-transmissive substrate is disposed so as to face the lightguiding plate 1, and a pair of electrodes 11 b is formed on theelectrode-formed surface 11 d on a side opposite to the light emissionsurface 11 c.

The vertical, lateral and height dimensions of the light emittingelement 11 have no requirement in their sizes, but it is preferable touse the semiconductor light emitting element 11 having each of verticaland lateral dimensions of 1000 μm or less in a plan view, it is morepreferable to use the light emitting element 11 having each of verticaland lateral dimensions of 500 μm or less in a plan view, and it is stillmore preferable to use the light emitting element 11 having each ofvertical and lateral dimensions of 200 μm or less in a plan view. Such alight emitting element 11 can realize a high-definition image at thetime of local dimming of the liquid crystal display device 1000. Whenthe light emitting element 11 has vertical and lateral dimensions of 500μm or less, the light emitting element 11 can be provided at low cost,and therefore the cost of the light emitting module 100 can be reduced.When the light emitting element 11 has vertical and lateral dimensionsof 250 μm or less, the upper surface of the light emitting element 11has a small surface area, and therefore the amount of light emitted fromthe lateral surface of the light emitting element 11 is relativelylarge. That is, such a light emitting element 11 tends to emit light ina batwing shape, and is therefore preferably used for the light emittingmodule 100 of this embodiment in which the light emitting element 11 isbonded to the light guiding plate 1, and a distance between the lightemitting element 11 and the light guiding plate 1 is short.

The light guiding plate 1 can be provided with the optically functionalportion 1 a having reflection and diffusion functions, such as a lens.The light guiding plate 1 can laterally spread light from the lightemitting element 11 to uniform the light emission intensity in thesurface of the light guiding plate 1. However, in the light guidingplate 1 with a plurality of optically functional portions 1 a formed atthe corresponding positions of a plurality of light emitting elements11, it may be difficult to maintain corresponding positions of all thelight emitting elements 11 and optically functional portions 1 aaccurately. Particularly, in the case of a structure in which a largenumber of small light emitting elements 11 are provided, it is difficultto maintain corresponding positions of all the light emitting elements11 and optically functional portions 1 a accurately. Deviation ofcorresponding positions of the light emitting element 11 and theoptionally functional portion 1 a weakens the function of the opticallyfunctional portion 1 a to sufficiently spread light. Thus brightness onthe surface is partially reduced, thereby leading to non-uniformity inluminance. Particularly, in a method including combining light guidingplates 1 after mounting the light emitting element 11 on a wiringsubstrate, it is necessary to give consideration to each of positionaldeviation of the wiring substrate and the light emitting elements 11 andpositional deviation of the light guiding plate 1 from the opticallyfunctional portions 1 a in a planar direction and a stacking direction.Thus there is a possibility that optical axis of the light emittingelement 11 and optical axis of the optically functional portion 1 a areless likely to be coincide with each other.

The light emitting module 100 in this embodiment has a structure inwhich the recesses 1 b and the optically functional portions 1 a areprovided on the light guiding plate 1, and the light emitting elementunits 3 are respectively disposed in the recesses 1 b, so that both thelight emitting elements 11 and the optically functional portions 1 a canrespectively be disposed with high accuracy. Accordingly, light from thelight emitting element 11 can be made uniform accurately by theoptically functional portion 1 a to obtain a high-quality light sourcefor backlight with little luminance non-uniformity and colornon-uniformity.

In the light guiding plate 1 with the optically functional portion 1 aprovided on a surface on a side opposite to the recess 1 b in which thelight emitting element 11 is disposed, the optically functional portion1 a is provided at the position of the recess 1 b in which the lightemitting element 11 is disposed in perspective plan view, so thatpositioning of the light emitting element 11 and the opticallyfunctional portion 1 a can be further facilitated to dispose both thelight emitting element 11 and the optically functional portion 1 a withsubstantially no relative position displacement.

As the light emitting element 11, the rectangular light emitting element11 having a square shape or oblong shape in a plan view is used. For thelight emitting element 11 to be used for a high-definition liquidcrystal display device, it is preferable that an oblong light emittingelement is used, and the shape of the upper surface of the lightemitting element has a long side and a short side. In the case of ahigh-definition liquid crystal display device, the number of lightemitting elements to be used is several thousands or more, and a lightemitting element mounting step is an important step. Even if arotational shift (e.g. a shift in a direction of ±90 degrees) occurs insome of a plurality of light emitting elements in the light emittingelement mounting step, the shift is easily visually observed when lightemitting elements having an oblong shape in a plan view are used. Inaddition, a p-type electrode and an n-type electrode can be formed at adistance from each other, and therefore wiring 21 as described later canbe easily formed. On the other hand, when light emitting elements 11having a square shape in a plan view are used, small light emittingelements 11 can be manufactured with high mass productivity. The density(i.e., arrangement pitch) of light emitting elements 11, in other words,the distance between light emitting elements 11 may be, for example, ina range of about 0.05 mm to 20 mm, preferably about 1 mm to 10 mm.

In the light emitting module 100 with a plurality of light emittingelement units 3 disposed on the light guiding plate 1 having a pluralityof recesses 1 b, light emitting element units 3 are two-dimensionallyarranged in a plan view of the light guiding plate 1. Preferably, aplurality of light emitting element units 3 is provided in recesses 1 bwhich are tow-dimensionally arranged along two orthogonal directions, inother words, the x-direction and the y-direction as shown in FIG. 2. Thex-direction arrangement pitch p_(x) and the y-direction arrangementpitch p_(y) of recesses 1 b in which a plurality of light emittingelement units 3 is disposed may be equal between the x-direction and they-direction as shown in the example in FIG. 2, or may be differentbetween the x-direction and the y-direction. In addition, the twodirections of arrangement are not necessarily perpendicular to eachother. In addition, x-direction or y-direction arrangement pitches arenot necessarily equal, and may be unequal. For example, recesses 1 b inwhich light emitting element units 3 are disposed may be arranged suchthat the distance increases as approaching toward the outer edge fromthe center of the light guiding plate 1. The pitch between lightemitting element units 3 disposed in recesses 1 b is a distance betweenthe optical axes, in other words, the centers, of light emitting elementunits 3.

For the light emitting element 11, a known semiconductor light emittingelement can be used. In this embodiment, the light emitting element 11is exemplary explained as a facedown type light emitting diode. Thelight emitting element 11 emits, for example, blue light. For the lightemitting element 11, an element which emits light other than blue lightcan also be used, and, a faceup type light emitting element can also beused. A plurality of light emitting elements respectively emit light ofdifferent colors may be used as the light emitting element 11. Lightemitted from the light emitting element 11 is adjusted its color at thewavelength conversion portion 12 before exiting outside.

As the light emitting element 11, an element which emits light having acertain wavelength can be selected. For example, as an element whichemits blue or green light, a light emitting element using anitride-based semiconductor (In_(x)Al_(y)Ga_(1−x−y)N, 0≤X, 0≤Y, X+Y≤1)or GaP can be used. As an element which emits red light, a lightemitting element including a semiconductor such as GaAlAs or AlInGaP canbe used. Further, semiconductor light emitting elements composed ofmaterials other than those described above can also be used. A lightemission wavelength can be variously selected according to the materialof a semiconductor layer and the degree of mixed crystal thereof. Thecomposition, color of light emission, size and number of light emittingelements to be used may be appropriately selected according to apurpose.

Light Adjustment Portion 10

In this embodiment, the light emitting element unit 3 is provided withthe light adjustment portion 10 in which the color of light emitted fromthe light emitting element 11 is adjusted before the light is incidentto the light guiding plate 1. The light adjustment portion 10 includesthe wavelength conversion portion 12 for adjusting the color of lightemitted by the light emitting element 11. The light adjustment portion10 is bonded to the light emission surface 11 c of the light emittingelement 11 to adjust the color of light emitted by the light emittingelement 11. The light adjustment portion 10 preferably includes thewavelength conversion portion 12 and the light diffusion portion 13. Inthe light adjustment portion 10, the wavelength conversion portion 12 isbonded to the light diffusion portion 13, and the wavelength conversionportion 12 is disposed on the light emitting element 11 side. In thelight adjustment portion 10 can also be configured by stacking aplurality of wavelength conversion portions 12 and light diffusionportions 13. In the light emitting module 100 of this embodiment, thelight adjustment portion 10 is disposed in the recess 1 b of the lightguiding plate 1, and used as the insertion portion 17 for the lightemitting element unit 3. The light adjustment portion 10 transmits lightentered from the light emitting element 11 before the light enters thelight guiding plate 1. For the purpose of, for example, thinning thelight emitting module 100 the light adjustment portion 10 is positionedinside the recess 1 b of the light guiding plate 1, and disposed in therecess 1 b without protruding from a plane flush with the second mainsurface 1 d as shown in FIG. 3. The light adjustment portion 10 shown inFIG. 3 has a thickness equal to the depth of the recess 1 b, and thesurface of the light adjustment portion 10 is flush with the second mainsurface 1 d. Alternatively, the light adjustment portion may bepositioned inside the recess, and have such a thickness that the lightadjustment portion slightly protrude from a plane flush with the secondmain surface of the light guiding plate (not shown).

In the light emitting element unit 3 shown in FIG. 3, the outline of thelight adjustment portion 10 is larger in size than the outline of thelight emitting element 11. In the light emitting element unit 3, alllight emitted from the light emission surface 11 c of the light emittingelement 11 is transmitted through the light adjustment portion 10 beforethe light enters the light guiding plate 1, so that color non-uniformitycan be reduced.

The wavelength conversion portion 12 contains a wavelength conversionmaterial added to a base material. The light diffusion portion 13contains a diffusion material added to a base material. Examples ofmaterial for the base material can be a light transmissive material suchas an epoxy resin, a silicone resin, a mixed resin thereof, or glass.From the viewpoint of light resistance of the light adjustment portion10 and ease of forming, a silicone resin selected as the base materialis beneficial. The base material for the light adjustment portion 10 ispreferably a material having a refractive index higher than the materialfor the light guiding plate 1.

Examples of the wavelength conversion material contained in thewavelength conversion portion 12 include YAG fluorescent materials,β-sialon fluorescent materials, and fluoride-based fluorescent materialssuch as KSF-based fluorescent materials. In particular, when varioustypes of wavelength conversion members are used for one wavelengthconversion portion 12, more preferably, the wavelength conversionportion 12 contains a β-sialon fluorescent material which emits greenishlight and a fluoride-based fluorescent material such as a KSF-basedfluorescent material which emits red light, the color reproduction rangeof the light emitting module can be expanded. In this case, it ispreferable that the light emitting element 11 includes a nitridesemiconductor (In_(x)Al_(y)Ga_(1−x−y)N, 0≤X, 0≤Y, X+Y≤1) capable ofemitting short-wavelength light that can efficiently excite thewavelength conversion member. For example, the wavelength conversionportion 12 may contain a KSF-based fluorescent material (i.e., redfluorescent material) in an amount of 60% by weight or more, preferably90% by weight or more so that red light can be obtained in use of thelight emitting element 11 which emits blue light. That is, thewavelength conversion portion 12 may contain a wavelength conversionmember which emits light of specific color, so that the light emittingelement units emit light of specific color. The wavelength conversionmaterial may be a quantum dot. In the wavelength conversion member 12,the wavelength conversion material may be disposed in any manner. Forexample, the wavelength conversion material may be substantially evenlydistributed, or unevenly distributed. Alternatively, a multilayer eachcontaining at least one wavelength conversion member may be provided.

For the light diffusion portion 13, for example, a material includingthe above-described resin material to which white inorganic particles ofSiO₂, TiO₂ or the like are added can be used.

Encapsulating Resin 15

The light emitting module 100 shown in FIG. 3 is provided by bonding theencapsulating resin 15 to the second main surface 1 d of the lightguiding plate 1. Preferably, the encapsulating resin 15 is formed usinga white resin in which white powder and the like as an additivereflecting light is added to a transparent resin. The encapsulatingresin 15 of white resin reflects light emitted from the outer peripheralportion or the electrode surface of the light emitting element 11, lightemitted from the back surface of the light adjustment portion 10, lightemitted from the back surface of the bonding wall 19, and light emittedfrom the second main surface 1 d of the light guiding plate 1, so thatlight emitted from the light emitting element 11 can effectively exitoutside from the first main surface 1 c of the light guiding plate 1. Inthe light emitting module 100 shown in FIG. 3, the encapsulating resin15 is sectioned into a first encapsulating resin 15A and a secondencapsulating resin 15B. In the light emitting module 100 in thedrawing, the encapsulating resin 15 is sectioned into the firstencapsulating resin 15A integrally formed with the light emittingelement unit 3, and the second encapsulating resin 15B bonded to thesecond main surface 1 d of the light guiding plate 1. However, theencapsulating resin may have an integral structure without beingsectioned into the first encapsulating resin 15A and the secondencapsulating resin 15B. In this case, the light emitting module ismanufactured in the following manner: a light emitting element unitprovided with no first encapsulating resin is bonded to a light guidingplate, and thereafter an encapsulating resin is bonded to a second mainsurface of the light guiding plate.

The light emitting module 100 in which the first encapsulating resin 15Aand the second encapsulating resin 15B are sectioned is manufacturedsuch that the first encapsulating resin 15A is bonded to the lightemitting element 11 and the light adjustment portion 10 to form thefirst encapsulating resin 15A into a block having an integral structurewith the light emitting element 11 and the light adjustment portion 10in a process of manufacturing the light emitting module 100. The secondencapsulating resin 15B is bonded to the second main surface 1 d of thelight guiding plate 1 such that the light emitting element unit 3provided with the first encapsulating resin 15A is bonded to the lightguiding plate 1, and then the second encapsulating resin 15B fills gapsbetween first encapsulating resins 15A.

The first encapsulating resin 15A and the second encapsulating resin 15Bare in contact with each other. Further, the first encapsulating resin15A is in contact with the light emitting element 11. The firstencapsulating resin 15A is present on the periphery of the lightemitting element 11, and embeds the light emitting element 11. Theelectrodes 11 b of the light emitting element 11 are exposed from thesurface of the first encapsulating resin 15A. The outer lateral surfacesof the first encapsulating resin 15A are flush with the outer lateralsurfaces of the light adjustment portion 10, and the first encapsulatingresin 15A is also in contact with the light adjustment portion 10. Thefirst encapsulating resin 15A is a part of the light emitting elementunit 3 bonded to the light emitting element 11 and the light adjustmentportion 10 as an integral structure, and the first encapsulating resin15A is bonded to the light guiding plate 1. The first encapsulatingresin 15A is preferably formed using a white resin, and the firstencapsulating resin 15A is capable of improving the light emissionefficiency of the light emitting module 100 by reflecting light emittedin a direction toward the outer lateral surfaces of the light emittingelement 11. The second encapsulating resin 15B is in contact with thefirst encapsulating resin 15A at a boundary between the second mainsurface 1 d of the light guiding plate 1 and the back surface (i.e., asurface close to the light emitting element 11) of the bonding wall 19.The second encapsulating resin 15B is provided on a surface that isflush with a surface of the first encapsulating resin 15A on which theelectrodes 11 b are exposed. The second encapsulating resin 15B isbonded to the second main surface 1 d of the light guiding plate 1, towhich the light emitting element unit 3 having the first encapsulatingresin 15A as an integral structure is bonded, so that the secondencapsulating resin 15B is provided between first encapsulating resins15A.

The second encapsulating resin 15B is stacked on the light guiding plate1 to reinforce the light guiding plate 1. In addition, the secondencapsulating resin 15B is preferably formed using a white resin, andreflect light to efficiently introduce light emitted from the lightemitting element 11 into the light guiding plate 1, to thereby increasethe light output of the first main surface 1 c of the light guidingplate 1. Furthermore, the second encapsulating resin 15B formed using awhite resin can serve as both a protection member for the light emittingelement 11 and a reflection layer on the second main surface 1 d of thelight guiding plate 1, resulting in reduction in the thickness of thelight emitting module 100.

For the encapsulating resin 15, a white resin having a reflectivity of60% or more, preferably 90% or more, with respect to light emitted fromthe light emitting element 11 is suitable. The encapsulating resin 15 ispreferably formed using a resin containing a white pigment such as whitepowder. In particular, a silicone resin containing inorganic whitepowder of titanium oxide or the like is preferable. Accordingly, aninexpensive material such as titanium oxide is used in a large amountfor a member used in a relatively large amount to cover a surface of thelight guiding plate 1, so that the cost of the light emitting module 100can be reduced.

Light-Transmissive Bonding Member

In the light emitting module 100 shown in FIG. 3, a light-transmissivebonding member is used to bond the wavelength conversion portion 12 andthe light diffusion portion 13, the light adjustment portion 10 and thelight emitting element unit 3, and the light emitting element unit 3 andthe light guiding plate 1. The light-transmissive bonding member bondsthe wavelength conversion portion 12 to the light diffusion portion 13to form the light adjustment portion 10, and bonds the light adjustmentportion 10 to the light emitting element 11 to form the light emittingelement unit 3. A light-transmissive bonding member 16A is the bondingagent 14 for bonding the light emitting element unit 3 to the bottom ofthe recess 1 b of the light guiding plate 1. This light-transmissivebonding member 16A bonds the light emitting element unit 3 to the lightguiding plate 1. The light-transmissive bonding member 16A is also thebonding agent 14 filling the ring gap 18 between the inner surfaces ofthe recess 1 b and the insertion portion 17 for the light emittingelement unit 3. This light-transmissive bonding member 16A forms thebonding wall 19 to bond the light adjustment portion 10 to the innersurface of the recess 1 b.

The light-transmissive bonding member has a light transmittance of 60%or more, preferably 90% or more. The light-transmissive bonding member16A propagates light emitted from the light emitting element 11. Thelight-transmissive bonding member 16A may contain one or more additives,such as a light diffusion material or white powder that reflects light.Alternatively, the light-transmissive bonding member 16A may be formedusing only a light-transmissive resin material which does not contain alight diffusion member, white powder or the like.

As a material for the light-transmissive bonding member, alight-transmissive thermosetting resin material such as an epoxy resinor a silicone resin, or the like can be used.

Process of Manufacturing Light Emitting Module 100

FIGS. 9A to 9D and 10A to 10D show a process of manufacturing the lightemitting element unit 3 according to this embodiment.

In the steps shown in FIGS. 9A and 9B, the wavelength conversion portion12 and the light diffusion portion 13 are stacked to form the lightadjustment portion 10.

In the step shown in FIG. 9A, a first sheet 31 obtained by attaching thewavelength conversion portion 12 to a surface of a base sheet 30 with auniform thickness, and a second sheet 32 obtained by attaching the lightdiffusion portion 13 to a surface of the base sheet 30 with a uniformthickness are stacked with the wavelength conversion portion 12 bondedto the light diffusion portion 13. The wavelength conversion portion 12is bonded to the light diffusion portion 13 with a light-transmissivebonding member. The wavelength conversion portion 12 and the lightdiffusion portion 13 are detachably attached to the base sheet 30 with,for example, an adhesive layer interposed between them.

Further, in the step shown in FIG. 9B, the base sheet 30 of the secondsheet 32 is detachably attached to a plate 33, and the base sheet 30bonded to the wavelength conversion portion 12 of the first sheet 31 isseparated.

In the step shown in FIG. 9C, the light emitting element 11 is bonded tothe light adjustment portion 10. The light emitting element 11 is bondedto the light adjustment portion 10 with the light emission surface 11 cof the light emitting element 11 facing the light adjustment portion 10.The light emitting element 11 is bonded to the wavelength conversionportion 12 of the light adjustment portion 10 at a predeterminedinterval. Light emitting elements 11 are bonded to the light adjustmentportion 10 with a light-transmissive bonding member interposedtherebetween. The light-transmissive bonding member is applied to asurface of the light adjustment portion 10 or a surface of the lightemitting element 11 to bond the light emitting element 11 to the lightadjustment portion 10. FIG. 9C shows a state in which an appliedlight-transmissive bonding member 16B sticks out to the periphery of thelight emitting element 11 to bond the light emitting element 11 to thelight adjustment portion 10. The intervals between light emittingelements 11 can be determined to such a dimension that the outline ofthe light adjustment portion 10 has a predetermined size after cuttingregions between light emitting elements 11 as shown in FIG. 10D. This isbecause the intervals between light emitting elements 11 determine theoutline of the light adjustment portion 10.

In the step shown in FIG. 9D, the first encapsulating resin 15A isformed so as to embed the light emitting element 11. The firstencapsulating resin 15A is preferably formed using a white resin. Thefirst encapsulating resin 15A formed using a white resin is supplied toa surface of the light adjustment portion 10, and cured with the lightemitting element 11 embedded therein. The first encapsulating resin 15Ais supplied with such a thickness that the light emitting element 11 isfully embedded. In the drawing, the first encapsulating resin 15A issupplied with such a thickness that the electrodes 11 b of the lightemitting element 11 are embedded.

In the step shown in FIG. 10A, the cured white resin is polished toexpose the electrode 11 b of the light emitting element 11.

Electrode terminals 23 may be formed on the electrodes 11 b of the lightemitting element 11 using a metal film. In this case, for example, inthe step shown in FIG. 10B, a metal film 22 is provided on a surface ofthe first encapsulating resin 15A. The metal film 22 can be formed, forexample, by providing a metal film of copper, nickel, gold or the likeon a surface of the first encapsulating resin 15A, by sputtering or thelike, and connected to the electrode 11 b.

In the step shown in FIG. 10C, a part of the metal film 22 is removedsuch that the remaining parts of the metal film 22 are formed on theelectrodes 11 b to serve as the electrode terminal 23 for the lightemitting element unit 3. Removal of the metal film 22 can be performedby dry etching, wet etching, laser ablation or the like.

In the step shown in FIG. 10D, the first encapsulating resin 15A formedusing a white resin and a layer to be the light adjustment portion 10are cut, and separated into the individual light emitting element units3. In each of the separated light emitting element units 3, the lightemitting element 11 is bonded to the light adjustment portion 10, thefirst encapsulating resin 15A is provided on the periphery of the lightemitting element 11, and the electrode terminals 23 are exposed from asurface of the first encapsulating resin 15A.

The light emitting element units 3 manufactured in the above steps arebonded to the recesses 1 b of the light guiding plate in the steps shownin FIGS. 11A to 11C and 12A to 12C.

The light guiding plate 1 is formed using polycarbonate. As shown inFIGS. 11A and 11B, the light guiding plate 1 is formed by molding athermoplastic resin such as polycarbonate, forming the recess 1 b on thesecond main surface 1 d, and providing the inverted cone-shapedoptically functional portion 1 a on the first main surface 1 c. Thelight emitting element unit 3 is bonded to the recess 1 b of the lightguiding plate 1. The light emitting element unit 3 is bonded to thelight guiding plate 1 by inserting the light adjustment portion 10 intothe recess 1 b in which the liquid light-transmissive bonding member 16Ais supplied in an uncured state, and curing the light-transmissivebonding member 16A. The light emitting element unit 3 is bonded to thelight guiding plate 1 by inserting the light adjustment portion 10accurately to the center of the recess 1 b, and curing thelight-transmissive bonding member 16A. The amount of the uncuredlight-transmissive bonding member 16A to be applied to the recess 1 bmay be adjusted such that the light-transmissive bonding member 16A isforced out into the ring gap 18 to make the surface of the bonding wall19 substantially flush with the second main surface 1 d of the lightguiding plate 1 at the time of bonding the light emitting element unit 3to the light guiding plate 1. Alternatively, filling the ring gap 18with the uncured light-transmissive bonding member can be performedafter the light emitting element units 3 are bonded to the light guidingplate 1, and in this case also the surface of the bonding wall 19 can beflush with the second main surface 1 d of the light guiding plate 1.Therefore, the amount of the uncured light-transmissive boding member16A initially supplied into the recess 1 b before bonding the lightemitting element unit 3 to the recess 1 b is such an amount that thesurface of the bonding wall 19 is positioned lower than the second mainsurface 1 d of the light guiding plate 1, in other words, such a smallamount that the surface of the light-transmissive bonding member 16A ispositioned within the ring gap 18. Then the light emitting element unit3 is bonded to the light guiding plate 1, thereafter thelight-transmissive bonding member is supplied into the ring gap 18 tomake the surface of the bonding wall 19 substantially flush with the ofthe second main surface 1 d of the light guiding plate 1.

The light-transmissive bonding member 16A that bonds the lightadjustment portion 10 to the bottom of the recess 1 b is in contact withthe surfaces of the light adjustment portion 10 and the bottom of therecess 1 b, and cured to bond the surface of the light adjustmentportion 10 to the bottom of the recess 1 b. Further, thelight-transmissive bonding member 16A forced out from a gap between thelight adjustment portion 10 and the bottom of the recess 1 b forms thebonding wall 19, so that the outer lateral surfaces of the lightadjustment portion 10 is bonded to the inner lateral surfaces of therecess 1 b. In this manufacturing method, the uncured liquidlight-transmissive bonding member 16A filling the recess 1 b is forcedout into the ring gap 18 to form the bonding wall 19. Also, thelight-transmissive bonding member 16A filling the recess 1 b is used asthe bonding agent 14, and therefore the filling amount of thelight-transmissive bonding member 16A needs to be adjusted so that thebonding wall 19 is substantially flush with the second main surface 1 dof the light guiding plate 1. When the filling amount of thelight-transmissive bonding member 16A is small, the surface of thebonding wall 19 is positioned lower than the second main surface 1 d ofthe light guiding plate 1 as shown in FIG. 7. Conversely, when thefilling amount of the light-transmissive bonding member 16A is large,the bonding wall 19 runs out from the ring gap 18, so that the surfaceof the bonding wall 19 protrudes from the second main surface 1 d of thelight guiding plate 1 as shown in FIG. 8. When the surface of thebonding wall 19 is not flush with the second main surface 1 d of thelight guiding plate 1, light distribution on the periphery of a lightemitting portion is less likely to be desirable. This is because thelight-transmissive bonding member running out from the recess 1 b or agap that is not filled with the light-transmissive bonding member causesundesirable light distribution. The filling amount of thelight-transmissive bonding member 16A is adjusted so that the bondingwall 19 is substantially flush with the second main surface 1 d of thelight guiding plate 1, because a slightly uneven filling amount causesdeviation of relative positions of the bonding wall 19 and the secondmain surface 1 d of the light guiding plate 1.

In the light emitting module 100 of this embodiment, the volume of thebonding wall 19 is larger than a partial volumetric capacity in therecess, which is defined as a partial volume of the light emittingelement unit 3 disposed or overlapped in the recess 1 b. Therefore thepartial volumetric capacity in the recess 1 b is substantially the sameas the volume of the light adjustment portion 10 of the light emittingelement unit 3, since the light adjustment portion 10 is dipped in thebonding agent 14 thus the light adjustment portion 10 of the lightemitting element unit 3 is positioned in the recess 1 b as shown in FIG.11B. Such configuration can prevent or alleviate the deviation ofrelative position between the surface level of the bonding wall 19 andthe second main surface 1 d of the light guiding plate 1 caused byunevenness of the supplying amount of the light-transmissive bondingmember 16A. Therefore, in this embodiment, the volume of the entirebonding wall 19 is larger than the volume of the light adjustmentportion 10. By making the volumetric capacity of the bonding wall 19being larger than that of the insertion portion 17, i.e., the lightadjustment portion 10 of the light emitting element unit 3, it canreduce level difference of the surfaces of the bonding wall 19 to thesecond main surface 1 d of the light guiding plate 1 caused by avariance in amount of the bonding agent 14 (to be the light-transmissivebonding member 16A) supplied in the recess 1 b.

As a specific example, the inner surface outline of a recess is aquadrangular shape having a length of 0.6 mm on each side, with a depthof 0.2 mm, the outline of a light adjustment portion is a quadrangularshape having a length of 0.5 mm on each side, with a thickness of 0.2mm, and the light adjustment portion is disposed in the recess. In thiscase, the volumetric capacity inside the recess of the light emittingelement unit is 0.05 mm³, and the volume of the entire bonding wall 19is 0.022 mm³, so that the volume of the entire bonding wall 19 is abouta half of the recess internal volume.

For maintaining the level difference of the surfaces of the bondingwalls 19 within ±0.01 mm in this structure, the filling amount of thelight-transmissive bonding member needs to be extremely accuratelycontrolled to within ±0.0036 mm³.

As a comparative example, the inner surface outline of the recess 1 b isa quadrangular shape having a length of 1.0 mm on each side, with thesame depth as that described above, the volumetric capacity inside therecess is likewise 0.05 mm³, and therefore the volume of the entirebonding wall 19 is 0.15 mm³ which is about 3 times the recess internalvolume. Then for adjusting the level difference of the surface of thebonding wall 19 to within ±0.01 mm, tolerance of the filling amount ofthe light-transmissive bonding member may be within ±0.01 mm³, which isabout 2.8 times as large as that described above.

Thus, in the light emitting module 100, the volumetric capacity of thering gap 18 is increased to increase the total volume of the bondingwall 19, even if the amount of the light-transmissive bonding member 16Asupplied in the recess 1 b is slightly different, the surfaces of thebonding walls 19 are likely to be even, whereby such surfaces aresubstantially flush with the surface of the second main surface 1 d ofthe light guiding member 1. Further, the thick bonding wall 19 transmitslight radiated from the light adjustment portion 10 before the light isguided to the light guiding plate 1, and therefore by a structure inwhich the thick bonding wall 19 different from the light guiding plate 1is stacked between the light guiding plate 1 and the light adjustmentportion 10, light is more uniformly dispersed, and exits to outside fromthe light guiding plate 1. The light emitting module can be manufacturedby bonding the light emitting element units 3 to the recesses 1 brespectively, supplying the light-transmissive bonding member 16A toform the bonding walls 19 having surfaces positioned lower than thesecond main surface 1 d of the light guiding plate 1, thereaftersupplying the light-transmissive bonding member 16A to form the bondingwalls 19 having surfaces substantially flush with the second mainsurface 1 d of the light guiding plate 1 accurately. In thismanufacturing process also, even if the amount of the light-transmissivebonding member 16A supplied in the recess 1 b is slightly different, thesurface of the bonding walls 19 is likely to be even, whereas suchsurfaces are substantially flush with the surface of the second mainsurface 1 d of the light guiding member 1.

After the light emitting element unit 3 is bonded to the light guidingplate 1, the second encapsulating resin 15B is formed on the second mainsurface 1 d of the light guiding plate 1 in the step shown in FIG. 11C.The second encapsulating resin 15B is formed using a white resin withsuch a thickness that the light emitting element unit 3 is embeddedtherein.

In the step shown in FIG. 12A, the surface of the cured secondencapsulating resin 15B is polished to expose the electrode terminal 23to the surface.

In the step shown in FIG. 11C, the second encapsulating resin 15B isformed with such a thickness that the light emitting element unit 3 isembedded therein, but the second encapsulating resin 15B can be formedwith such a thickness that the surface of the second encapsulating resin15B is flushes with the surfaces of the electrode terminals 23, or at aposition lower than the surfaces of the electrode terminals 23, in orderto omit the polishing step.

In the step shown in FIG. 12B, an electrically conductive film 24 isstacked on the surface of the encapsulating resin 15. In this step, ametal film 24 of Cu/Ni/Au is formed on substantially the entire surfaceof each of the electrode terminals 23 of the light emitting element 11and the encapsulating resin 15 by sputtering.

In the step shown in FIG. 12C, a part of the electrically conductivefilm 24 is removed, and each of the light emitting elements 11 iselectrically connected through the electrically conductive film 24.

In the above steps, the light emitting module 100 is manufactured inwhich a plurality of light emitting element units 3 is bonded to onelight guiding plate 1. The light emitting module including the lightemitting bit 5 in which one light emitting element unit 3 is bonded toone light guiding plate 1′ can be manufactured by: providing the lightemitting element unit 3 as shown in FIGS. 9A to 9D and 10A to 10D;bonding the light emitting element unit 3 to one recess 1 b of the lightguiding plate 1 in the steps shown in FIGS. 11A and 11B; bonding thesecond encapsulating resin 15B to the light guiding plate 1 in the stepshown in FIG. 11C; polishing the surface of the second encapsulatingresin 15B to expose the electrode terminals 23 in the step shown in FIG.12A; stacking the electrically conductive film 24 in the step shown inFIG. 12B; and removing part of the electrically conductive film 24 toallow the separated electrically conductive film 24 to be individuallyprovided on the electrode terminals 23, thereby electrically connectingthe separated electrically conductive film 24 to the electrode terminals23 in the step shown in FIG. 12C.

A plurality of light emitting element units 3 may be connected by wiringso as to be driven independently of one another. The light emittingmodule may include a plurality of light emitting element unit groups,where the light guiding plate 1 is divided into a plurality of areas, aplurality of light emitting element units 3 mounted within one area isput into one group, and a plurality of light emitting element units 3 inthe group is electrically connected to one another in series or inparallel, and connected to the same circuit. By arranging light emittingelement units into groups as described above, a light emitting modulecapable of local dimming can be obtained.

One light emitting module 100 of this embodiment may be used as abacklight for one liquid crystal display device. Alternatively, aplurality of light emitting modules 100 may be arranged, and used as abacklight for one liquid crystal display device 1000. When a pluralityof small light emitting modules 100 is provided, and each subjected toinspection or the like, the yield can be improved as compared to a casewhere the large light emitting module 100 having a large number of lightemitting elements 11 mounted thereon is prepared.

The light emitting module 100 may include a wiring substrate 25 as shownin FIG. 13. The wiring substrate 25 is provided with, for example, anelectrically conductive member 26 covering a plurality of via holesprovided on an insulating base member, and a wiring layer 27electrically connected to the electrically conductive member 26 at bothmain surfaces of the base member. The electrodes 11 b are electricallyconnected to the wiring layer 27 via the electrically conductive member26.

One light emitting module 100 may be bonded to one wiring substrate.Alternatively, a plurality of light emitting modules 100 may be bondedto one wiring substrate. Accordingly, terminal electrodes for electricalconnection to the outside (e.g. connectors) can be integrated, in otherwords, it is not necessary to prepare terminal electrodes for each lightemitting module, and therefore the structure of the liquid crystaldisplay device 1000 can be simplified.

Furthermore, a plurality of wiring substrates, each of which is bondedto a plurality of light emitting modules 100, may be arranged, and usedas a backlight for one liquid crystal display device 1000. In this case,for example, a plurality of wiring substrates can be placed on a frameor the like, and each connected to an external power source using aconnector or the like.

A light-transmissive member having a function of light diffusion or thelike may be further stacked on the light guiding plate 1. In this case,when the optically functional portion 1 a is a hollow, the opening(i.e., a portion close to the first main surface 1 c of the lightguiding plate 1) of the hollow is closed, or a light-transmissive memberis provided without filling the hollow. Accordingly, a layer of air canbe provided in the hollow of the optically functional portion 1 a, sothat light from the light emitting element 11 can be favorably spread.

The light emitting module according to the present disclosure can beused as, for example, a backlight for a liquid crystal display device,lighting equipment or the like.

It should be apparent to those with an ordinary skill in the art thatwhile various preferred embodiments of the invention have been shown anddescribed, it is contemplated that the invention is not limited to theparticular embodiments disclosed, which are deemed to be merelyillustrative of the inventive concepts and should not be interpreted aslimiting the scope of the invention, and which are suitable for allmodifications and changes falling within the scope of the invention asdefined in the appended claims.

What is claimed is:
 1. A method of manufacturing a light emittingmodule, the method comprising: providing a light guiding plate having afirst main surface serving as a light emitting surface, and a secondmain surface opposite to the first main surface, the second main surfacedefining a recess thereon, and a light emitting element unit comprisinga light emitting element having a light emission surface and comprisingan electrode, and a light adjustment portion containing a fluorescentmaterial, the light emitting element being integrally bonded to thelight adjustment portion; fixing the light emitting element unit to thelight guiding plate by bonding the light adjustment portion to therecess; and forming wiring on the electrode of the light emittingelement.
 2. The method according to claim 1, wherein the recess formedon the second main surface comprises a plurality of recesses, whereinthe light emitting element unit comprises a plurality of light emittingelement units, and wherein the plurality of light emitting element unitsare each bonded to the plurality of recesses of the light guiding plateto bond the plurality of light emitting element units at predeterminedpositions on the light guiding plate.
 3. The method according to claim1, wherein in fixing the light emitting element unit to the lightguiding plate, the light emission surface of the light emitting elementis flush with the second main surface of the light guiding plate.
 4. Themethod according to claim 3, further comprising: forming a bonding wallwith a bonding agent supplied in a ring gap formed between inner lateralsurfaces of the recess and outer lateral surfaces of an insertionportion of the light emitting element unit disposed in the recess, theinsertion portion having an outline smaller than an inner surfaceoutline of the recess.
 5. The method according to claim 4, wherein avolumetric capacity of the ring gap is larger than a volume of theinsertion portion of the light emitting element unit.
 6. The methodaccording to claim 4, wherein a surface of the bonding wall issubstantially flush with the second main surface of the light guidingplate.
 7. The method according to claim 4, wherein the bonding agent isa light-transmissive resin.
 8. The method according to claim 1, whereinthe light emitting element unit is provided with a first encapsulatingresin which has outer lateral surfaces flush with the outer lateralsurfaces of the light adjustment portion, the first encapsulating resinembedding the light emitting element, and wherein the light emittingelement unit provided with the first encapsulating resin is bonded tothe light guiding plate.
 9. The method according to claim 8, wherein thefirst encapsulating resin includes a white resin.
 10. The methodaccording to claim 1, wherein in fixing the light emitting element unitto the light guiding plate, a second encapsulating resin for embeddingthe light emitting element unit is provided on the second main surfaceof the light guiding plate to which the light emitting element unit isbonded.
 11. A light emitting module comprising: a light-transmissivelight guiding plate having a first main surface serving as a lightemitting surface from which light exits and a second main surfaceopposite to the first main surface, the second main surface defining arecess thereon; and a light emitting element unit fixed to the recess ofthe light guiding plate, wherein the light emitting element unitcomprises: a light emitting element having a light emission surface anda light adjustment portion containing a fluorescent material, the lightadjustment portion being integrally bonded to the light emitting elementand having an insertion portion disposed in the recess, the insertionportion having an outline smaller in size than an inner surface outlineof the recess; and a bonding wall formed with a light-transmissivebonding agent filled in a ring gap formed between the insertion portionand the recess.
 12. The light emitting module according to claim 11,wherein a volumetric capacity of the ring gap is larger than a volume ofthe insertion portion of the light emitting element unit.
 13. The lightemitting module according to claim 11, wherein the light emittingelement unit comprises a first encapsulating resin which has outerlateral surfaces substantially flush with outer lateral surfaces of thelight adjustment portion, the first encapsulating resin embedding thelight emitting element.
 14. The light emitting module according to claim12, wherein the light emitting element unit comprises a firstencapsulating resin which has outer lateral surfaces substantially flushwith outer lateral surfaces of the light adjustment portion, the firstencapsulating resin embedding the light emitting element.
 15. The lightemitting module according to claim 13, further comprising a secondencapsulating resin in which the light emitting element unit is embeddedis stacked on the second main surface of the light guiding plate. 16.The light emitting module according to claim 14, further comprising asecond encapsulating resin in which the light emitting element unit isembedded is stacked on the second main surface of the light guidingplate.
 17. The light emitting module according to claim 15, wherein atleast one of the first encapsulating resin and the second encapsulatingresin contains a white resin.
 18. The light emitting module according toclaim 16, wherein at least one of the first encapsulating resin and thesecond encapsulating resin contains a white resin.